One of the difficulties with delivery of erodible materials into a fluid from a canister is that oftentimes the concentration of the materials delivered into the fluid varies in response to various factors besides the flow rate of fluid through the canisters. The problem of incorrect delivery rate may occur with systems for delivery of water dispersant into a body of water, which can be harmful. For example, where the concentration of the dispersant in the body of water needs to be maintained within a range to ensure the safety of the water for either consumption or recreational use such as in swimming pools, spas or the like as well as in systems where the erodible and dissolvable materials are used to maintain systems in a conditioned state to prevent bacterial growth. Since various factors including the type and state of the dispersant materials as well as other factors including the water temperature and water flow rates may have an effect on the proscribed release of dispersant from the dispenser one may not be able to ensure that the dispersant delivery rate remains within an acceptable range.
Typically, in an inline system the water flow rate through the inline dispenser is initially adjusted to deliver a proscribed amount of disperant into the body of water. It is generally assumed that as long as the water flow rate through the canister remains constant the disperant rate from the canister should also remain constant until the dispersant in the dispenser is exhausted. However, since the dispensing material within the canister is generally hidden from view one cannot readily observe if the dispersant is being properly dispensed. For example, in some cases the internal water flow effects such as the Coanda effect may cause water to flow through the passages within the canister without making sufficient contact with the dispersant in the canister. In other cases the state of the dispersant material may cause the dispersant rate to vary by preventing the water from coming into proper contact with the dispersant in the canister. Since such internal water effects may be transient and are not directly viewable in a canister the operator may not know that the concentration of dispersant has changed unless the concentration of dispersant is continually monitored, which in some systems is not feasible or practical. One of the methods of eliminating a problem such as bridging or caking is to change the composition of the dispersant while another may include monitoring temperatures to ensure that changes in temperature of do not result in caking or bridging within the dispenser. Thus, changes in the composition of the dispersant as well as the control of other factors which affect caking such as temperature may be used, however, such solutions can be costly and time consuming.